Your message doesn't carry conviction. If you are pro these activities, then you should say that the doctor should not use this mechanism as a money making scheme. He should not buy/sell kidneys, rather he should counsel poor people on the value of their organ, and provide guidance on a suitable amount if they wish to go ahead, and then make this person meet the client and organize the "sale". Your not suggesting this option shows that you approve of doctors becoming pimps.
Also you are talking about kidney patients, but not bothering to give a seconds pause to people who lost their kidneys for meager amounts. So yours is a one-sided view. Do buying/selling, but keep people informed and let them get a good deal. Are you willing to lose some organ of yours for a few thousand rupees just because it is not required? Is this not hypocrisy?